An ultra-thin gate dielectric film is developed using epitaxially grown crystalline HfO₂ in place of amorphous SiO₂. Owing to the large dielectric constant of crystalline HfO₂ which is 5 times larger than that of amorphous SiO₂, an ultra-thin electrical thickness of 0.5 nm is achieved by a 2.5 nm-thick epitaxial HfO₂ film. The leakage current is 6 orders lower than SiO₂. This technology is applicable to LSI manufacturing without difficulty, because it was developed based on the crystallization mechanism using LSI tools. Ultra-thin dielectric films contribute to the supply voltage reduction and thus the low power operation of integrated circuits.